write_val = read_val & ~mask;
ipath_write_kreg(dd, dd->ipath_kregs->kr_extctrl, write_val);
read_val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_extstatus);
write_val = read_val & ~mask;
ipath_write_kreg(dd, dd->ipath_kregs->kr_extctrl, write_val);
read_val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_extstatus);